1. Field of the Invention
This invention relates to mechanical walkers, and particularly to robotic walking mechanisms having six legs of equal length organized in an X-Y-Z axial relationship extending radially from a central sphere, wherein movement over a surface is accomplished by rotation of the legs and sphere. The invention also relates to a superstructure for conveyance of items supported by a plurality of such walkers.
2. Description of the Related Art
A great deal of effort and attention has been directed toward construction of mechanisms capable of horizontal movement. Myriad applications of the wheel have been designed and built, but they generally require a smooth surface especially as speeds increase. All wheel-reliant machines must incorporate a braking system to prevent movement on slanted or irregular surfaces. The National Aeronautics and Space Administration, universities, and independent research laboratories, have created sophisticated walking and movement devices which employ continuous belt-like tracks, such as used by tanks, numerous wheeled configurations, and sophisticated two-footed walking machines which require lateral support to remain upright. Despite these advances, a need remains for a simple device capable of forward movement which is stable on slanted or rough surfaces, and which has the capability of conveying objects to a remote location. Any such robotic movement device would have enhanced value if capable of being controlled remotely.
A mechanical walker according to the invention comprises a set of six legs of approximately equal length, extending radially from a central sphere and disposed in an X-Y-Z-type axial relationship. The legs and sphere, when placed on a horizontal surface, assume a natural rest position wherein three low legs rest on the surface, and three high legs extend upward in axial alignment with the three low legs. From the rest position, the legs and sphere can be moved in any of three directions coincident with the direction of extension of each of the high legs. In any one of the three selected directions, in rest position the two lower legs below the selected high leg are referred to as xe2x80x9canchor legs.xe2x80x9d Movement in the selected direction is accomplished by applying sufficient force on the mechanism to move the high leg forward, rotating the sphere (and legs), until the foot of the high leg rests on the surface with the ends of the two anchor legs. This movement represents a first movement cycle. The apparatus may then be moved in one of three new directions represented by the three xe2x80x9cnewxe2x80x9d high legs through a second movement cycle. Movement through the second cycle is identical to movement of the device through the first cycle, except that the three directions of movement available for the second cycle of movement are sixty degrees offset from the three directions of movement available at the beginning of the first cycle. Subsequent cycles of movement after the second cycle are available, the directions of movement for each cycle offset by sixty degrees from the directions of movement of the previous cycle.
A superstructure comprises a bearing member and shell. The bearing member provides a downward facing bearing surface having a curvature matching that of the outer surface of the sphere. The bearing surface rests against a top portion of the sphere. During each cycle of movement, the two rearward high legs sweep forward as the forward high leg rotates forward and downward to the end of the cycle. The orientation of the sphere is confined as discussed below so that the movement of the high leg through any cycle of movement is restricted to three vertical planes common with a center point of the sphere and offset from each other by one hundred twenty degrees. Hence, the rear high legs are also confined to defined sweep paths. The bearing member extends upwardly from the bearing surface in a six-sided scalloped pattern matching the sweep paths of the rearward high legs in each of the six possible directions of movement available through any two consecutive cycles of movement.
The shell comprises six inwardly biased pads for gripping the equatorial region of the sphere. Spaces between each adjoining pair of pads are sufficiently wide to accommodate the vertical movement of a high leg on its vertical path during a movement cycle. Slots in the shell extending upwardly from each of the spaces confine movement of the high legs to three vertical planes through each movement cycle. That is, they prevent horizontal drift of the high leg during the movement cycle. The shell also forms a plurality of scalloped surfaces between each pair of adjoining slots parallel to and spaced from the scalloped outer surface of the bearing member, defining therebetween sweep channels for preventing the rearward legs from lateral rotation during a movement cycle. The shell is joined to the bearing member, thereby holding the sphere by the six pads, against the bearing surface of the bearing member.
The bearing member includes six vertical bores. An actuating rod disposed in each bore has at its lower end a contact foot for engaging and pushing down a selected high leg. Forward movement is accomplished by pressing down one of the actuating rods, thereby bringing the contact foot into engagement with the selected high leg. Pushing the high leg down forces the mechanism to xe2x80x9cwalk overxe2x80x9d the two anchor legs until the high leg is brought into contact with the surface level of the anchor legs. The actuating rod is then retracted, and a succeeding cycle of movement is initiated by pushing down the actuating rod over a selected one of the three xe2x80x9cnewxe2x80x9d high legs.
A plurality of at least three mechanical walkers can support a platform, chassis, or other means for conveying any desired object. The force necessary for downward movement of the actuating rods can be supplied by numerous means well known to those skilled in the art.